Frank Zappa (1940-1993) is best remembered as the front man and lead guitarist of the Mothers of Invention, the avant-garde rock band that started developing a dedicated cult following in 1966 with the release of its debut album, "Freak Out!" The group's irreverent, anti-establishment anthems satirizing the status quo resonated with the emerging Hippie Generation's counter-cultural attitudes.

The long hair and rebel image overshadowed Frank's roots as a classical virtuoso influenced by such 20th Century greats as Edgar Varese and Igor Stravinsky. He began composing chamber music at the age of 14 and didn't write his first rock song with lyrics until after he turned 21.

Even after finding fame, Frank remained desperate to be taken seriously as an artist. Consequently, he quite obviously became quite frustrated over the course of his career by the constraints imposed by his packaging as a hippie rock idol.

An inveterate iconoclast, he was also very outspoken on subjects ranging from politics to drugs to the music business. And he often confounded journalists with his surprising stances on prevailing social issues. For example, he was extremely anti-drugs in an era when many of his fans and contemporaries were experimenting with marijuana, LSD and other so-called recreational narcotics.

In terms of his record company, he hated the fact that MGM had the nerve to censor his tunes without his permission. He further observed that, in general, "Musicians are regarded as useless adjuncts of society, unless you write a Coca-Cola jingle."

A free speech advocate, he felt that "Dirty words are a fantasy manufactured by government fanatics and religious organizations to keep people stupid." Just as suspicious of the Left and the Right, he asserted that "Any sort of political ideology that doesn't take into account people's differences is Fascistic."

Eat That Question is a reverential rockumentary directed by Germany's Thorsten Schutte. The informative film contains reams of archival footage featuring its loquacious subject expounding his personal philosophy. The intriguing biopic includes some performances, too, but the cerebral production proves far more fascinating when focusing on what made the man tick than on his music.

A riveting retrospective plumbing the depths of the brilliant mind of a Renaissance man underappreciated in his own time.